newbie question about the boil.

[cutnrun]

I am struggling to get hold of a boiler that i can use to boil over 5 gallons of for 90 min. I was just wondering the reason for the boil. appart from adding the hops is there a chemical reason for the boil. From my books i see that the sparge stops the endsyme action. If the boil is only to get the flavour, acids etc out of the hops and adjuncts can i boil half the wort with all of the hops?

like i said newbie question,

if you dont ask you dont know!

 

[Mephistopholes]

The boil is basically to isomerize the hop alpha acids (extract and lock in the bitterness)

It is possible to boil a smaller amount and liquor back but not nearly as effective.

say for example 10g hop gicves 10 IBU in 20 litres of wort (stay with me here i know these figures are a bit creative)
10g hop gives 16 IBU in 10 litres of wort

so once you liquor back the 10 litre boil to 20 litres you will be left with 8 IBU

now this was a long winded, fantastical and fairly non-sensical way of saying hop isomeration is less effective when used in proportinally larger quatities relative to the amount of wort.

You'll basically have to use more hops if you do smaller boils thus costing more money eventually, especially if you like a hoppy beer.

there are a lot of threads on here about building boilers cheaply. I would say its very easily acheivable to buy and build a 25 litre mash tun for £20-25 maybe even less if you really shop around.

I'm currently in the middle of building a 60 litre tun with two 3000w elements a lovely new ball valve and hop filter.

20 quid for the bucket (ive since seen an alternatiove for 6 quid )
8 quid for the elements (4 for one. free if youve got an old kettle knocking around)
8 quid for the ball valve and tank connectors ( you can get fully kitted out ones for this purpose on ebay or spend a little less build it yourself and go to screwfix)
10 quid or less on copper ( to be honest i think if id been a little more savvy i could have been closer to 3-4 quid on this)

so 46 quid for a 60 litre boiler. a 25 litre with one element and smaller hop strainer though would be much cheaper.

 

[Dunfie]

The boils does quite a bit more than just bring the alpha acids into solution. It drives off some of the undesirable compounds like DMS (dimethyl sulphide :sick: ), it helps the haze creating protiens precipitate and drop out of solution through the hot break. Also if you crash cool you induce the cold break which removes more of the haze creating protiens.

On top of all that the boil itself ensures that the wort is sterile and ready to receive your yeast.

 

Dunfie's got it spot on!
The boil also reduces the length so you can sparge all the sugars out and not worry about low gravity.

 

[thedrayman]

Over the years I've always done a 90 minute boil ("because the commercial breweries do") but I see some craft brewers only do a 60 minute one. Is a 60 minute rolling-boil adequate or is 90 minutes the 'ideal'?

 

[Aleman]

Over the years I've always done a 90 minute boil ("because the commercial breweries do") but I see some craft brewers only do a 60 minute one. Is a 60 minute rolling-boil adequate or is 90 minutes the 'ideal'?

"Boil to secure the hot break" . . . I fyopu get an adequate hot break and the wort is bright after 60 minutes then there is no need to boil longer . . .apart from hop isomerisation . . . which you take care of by adjusting your hopping rate to suit the new boil duration. . . We were boiling for 60 minutes at Wibblers . . . on both the 13KW 2BBL set up and the 48KW 18BBL setup